Field of the Invention and Related Art Statements
The present invention relates to a helmet with two-way radio communication faculty.
Such helmets can be advantageously used by workers who work within constructions such as underground electric power substations, buildings, underground streets and work at high points of power transmission towers and power distribution poles and general outdoor workings. With the aid of the helmets with two-way radio communication faculty, not only communication between workers who wear helmets, but also between workers and a supervisor or central control room can be effected.
The helmet with two-way radio communication faculty has been known and described in, for instance Canadian Patent No. 936,921 issued on Nov. 13, 1973. In this known helmet, a transmitter unit, a receiver unit and a battery unit are all arranged in a box-like housing and the housing is secured to an inner surface of a cap-like outer shell. Further an antenna is provided on an outer surface of the outer shell. In such a known helmet, since almost all components are arranged in the box-like housing dimension of the housing is liable to be large and weight of the helmet is liable to be heavy. Therefore, it is necessary to provide a relatively large space within the outer shell, so that the helmet becomes large. Further, the weight of the helmet is concentrated at its center, a user wearing the helmet feels wearness and a working efficiency of user might be decreased. Moreover, in this known helmet, the transmitter and receiver units are arranged in the same box-like housing, radio frequency energy might be supplied from the transmitter unit to the receiver unit to cause interference. Further, the known helmet has no shock absorbing member underneath the outer shell, and impermissible mechanical shock might be transferred to a head of the user.
Further, in the known helmet, since the antenna is provided on the outer surface of the outer shell, the antenna conductor might be easily exposed although the antenna is embedded in an electrically insulating plastic strip. Then the helmet could not be effectively protected against the electric shock under a high tension.